Microgravity stresses seedlings, but space crops can adapt

We tend to take gravity for granted, but it's played a key role in shaping the evolution of life on Earth. Living on the International Space Station (ISS) for months at a time takes its toll on the health of astronauts, and now a new study from the European Space Agency (ESA) has looked at how seedlings handle microgravity. The results show that the unusual conditions do stress the plants out, but they manage to adapt, which bodes well for the future of astronomical agriculture.

If humans are ever going to become an interplanetary species – a goal that Elon Musk has dedicated his life to reaching – we have to learn how to grow food in space. Weightlessness, excess radiation and a lack of water can all wreak havoc on space crops, so it's important to study how much of an issue those things will be, as well as how we (and the plants) might be able to leap those hurdles.

In the new study, the Columbus module on the ISS was home to some 1,700 thale cress seedlings. Since soil doesn't exactly work in low gravity, the seeds were grown in "cassettes" that could be monitored from Earth, with water, oxygen and light fed in. Their growth was monitored in real-time over the course of six days, before the sprouts were snap frozen to -80° C (-112° F) and transported back to Earth. Once on the ground, researchers analyzed both the images taken while the seeds grew, as well as the genes and molecules of the returned specimens.

Normally, the roots of plants grow downwards into the soil in search of water and nutrients, but in space the seedlings couldn't tell which way was down. That resulted in relatively random patterns of root growth, which is better than the possible alternative: that the seeds just didn't grow at all.

Although they managed to adapt, the genetic study revealed that the microgravity environment stressed the plants out. Certain genes that are usually expressed under stressful conditions, like heat, frost and salinity, were detected in higher number. But shining red light on the seeds seemed to counteract the negative effects of weightlessness and got the plants' cell growth back on track.

The behavior of the plants was clearly affected, but the results suggest that microgravity might not be the worst enemy of space crops – that honor probably goes to radiation or airlessness. Either way, the study gives some new insights into plant biology that could be put to use for planning food for longer space trips, or making hardier variations here on Earth to counter the ill effects of climate change.